According to Shires, it all started after a conversation she and Carlile had in Nashville. "We've been friends for a long time, man. I met her on a Cayamo cruise, I can't even remember when. A long time ago," the singer recalls. "We were at the Basement for some reason, and I told her about this idea I had called the Highwomen, and she was like, 'I love that idea!' and I was like, 'I want you to be in it. And I want you to help me run this, 'cause I'm terrible at business and stuff, and my voice isn't as great as yours.'

"And she was like, 'Yeah, man. I'll be in your band, the Highwomen,'" Shires goes on to say. "And then we asked Margo, and she said yeah."

On Thursday (Jan. 10), after several news outlets picked up the story, Shires admitted that she may have let the news slip a bit too soon: "I accidentally jumped the gun," she writes on Twitter. "Brandi and I do have something in the works and we will announce the exact details when it comes to fruition. Just wanted to let you know that nothing is official and this isn't news yet."

Shires also indicated in her interview that she and Carlile have written two songs together for a forthcoming project from the Highwomen, and that she was also writing music for the new trio with Jim Lauderdale. Shires admitted that she's also hoping for a wide range of guests and special cameos from other female artists.

As for the style of music the potential new group might aim for, Shires suggests that while each artist's solo career in roots music will remain a top priority, the trio might serve as an outlet for them to pursue a bit more of a classic country sound.

"What we wanna do is play more country music," she adds.

Should the Highwomen become an official project, the name is a nod to another country supergroup: The Highwaymen was formed by Johnny Cash, Kris Kristofferson, Waylon Jennings and Willie Nelson in the mid-1980s. The quartet released three albums together and earned a No. 1 song with "Highwayman."